Electromagnetic devices such as solenoid devices are in widespread use. In certain applications, there is a need to perform test and fault detection on solenoid operators. In many of these applications, the solenoid device is disposed at a remote location or is otherwise inaccessible. Prior art has attempted to solve this challenge but has been limited to voltage-drive applications (U.S. Pat. No. 4,321,946 "Armature Position Monitoring and Control Device" and U.S. Pat. No. 4,907,901 "Method and Apparatus for Measuring Displacement of a moveable Member of an Electromagnetic Device by Using Perturbations in the Device's Energizing Current") or has required separate and added sensors (U.S. Pat. No. 3,789,876 "Solenoid Valve with Electronic Position Indicator" and U.S. Pat. No. 4,692,678 "Closed Loop Servo Control System").
High response solenoids using current drive controllers require more sophisticated circuitry, in order to capture armature motion, that is not provided in the prior art. The invention herein described solves these problems.